Related Field
The present disclosure relates devices and a method for monitoring a display image in a transparent optical projection display. In particular the disclosure relates to devices and a method related to transparent optical projection displays, for monitoring the display image with a fiber optic face plate and an image sensor.
Description of Related Art
It is important that displays, especially transparent optical projection displays such as Head Up Displays, HUD, or Helmet Mounted Displays, HMD, show right information for a commander of a vehicle, such as a pilot of an aircraft. If the information on the display is misleading, this could result in fatal maneuvers. Examples of misleading information are wrong height information, wrong targeting information or a wrong horizon. An example of wrong height information is if a height of 1,000 foot instead of a real height of 7,000 foot would be displayed. Further misleading operation could be that important symbols overlap so that they are not readable, or at least not readable without any difficulties. Other examples of misleading information are misplaced symbols or symbols which are not placed at all.
To avoid that such misleading information is displayed, authorities responsible for aircrafts or air traffic have strict standards regarding functioning and controlling of graphic processing units, GPU. Developing GPUs which fulfil these standards and documenting these GPUs, or proving that these GPUs work as intended is, however, time and cost intensive.
In the recent years, commercial of-the-shelf, COTS, graphic processing units, GPU have become more and more powerful. Today, they have similar or often even higher performance than GPUs which are especially developed for aircraft industries. A disadvantage of these COTS GPUs is, however, that their internal structure often is not publicly available, so that a documented proof of their functionality, resulting in a certification for aircraft use, is not possible.
Therefore, in addition to preventing the obvious security issues with displaying the wrong information there is also a need to assure correct displaying for COTS GPUs in aircrafts to be able to use COTS GPU in aircrafts, and thus drastically lowering construction costs.
Traditionally, the generation of graphics is monitored by letting the GPU internally check for errors in the output image. This gives information regarding the functioning of the GPU but in the case of a malfunctioning GPU, errors in the displayed image may be missed.
There is always a need to improve the process to check for errors in the image for display to the pilot.